I blew my head gasket and my piston on the side where it blew has small imperfections all over the surface and what looks like a small chip on one corner.







Will this surface roughness cause a problem? It doesn't look like the small chip sticks out the side at all to contact the wall.

 

how does the head look in that cylinder? it looks like something got in there

 

There was a decent sized piece of the head gasket missing at that piston and my head bolts were only hand tight on that side so I was lifting the head pretty bad. I guess a piece of the head gasket got sucked in.

Head was resurfaced and cleaned by a machine shop and they also pulled the valves and said everything looked fine. Is it normal for Evo valves to stick out slightly below the base of the head? They couldn't resurface my head without pulling the valves because several stuck down so far.

 

that looks like detonation, knock, .
Maybe the knock caused the headgasket to blow

 

Yes, the valves should stick out a little.

As for the piston, it doesn't look too bad and if you're on a tight budget, you can still run it. But of course, I wouldn't suggest that and would suggest a rebuild but it's your money and your budget. Getting drop in piston and rods would suffice if you're nervous about it blowing up.

He said the head bolts were only hand tightened so I'm guessing the head bolts were loose and the head was lifted.

 

That's not from detonation. As AreSTG said, something got inside the combustion chamber.

 

 

The head bolts may have been loose, but its not because they were undertightened when they were installed. They were stretched, likely from detonation. I would be weary of running that piston, and the heads bolts would definitely be getting replaced, as well as having the car retuned. The marks on the piston are likely form something bouncing around in the chamber, that is not detonation pitting.

 

Looks like detonation pitting to me. Or you sucked a bag of sand into the chamber. What do the tops of the other pistons look like?

Things to look at after a heavy round of detonation abuse:
Tune...
Stretched head studs
Beat to hell main/rod bearings
Piston pin bores ovalized
Piston structurally compromised
Wrist Pins potentially bent
Rods potentially bent
TUNE!!!!

That's ideal world check out...lots of guys manages to burn holes in cylinder heads from sever detonation and yet put the motor back together with the same parts and they last a while still.

 

Google det pitting, that is not it. Det pitting erodes the outer edge of the crown, eventually breaking it off into the ring land..

 

The other pistons look fine. A little dirty but none of the surface imperfections like that piston. I was experiencing a problem with a bad misfire before I blew my freeze plug. I am not sure how long the head gasket was blown before the freeze plug blew but that's what led me to belie I also had a blown head gasket and pulled the head.

 

No thanks...I know what it looks like and I understand the mechanics of it.

Sure...it gets to that point after a LOT of minor detonation activity. It doesn't just magically happen all at once though. You are simply seeing the initial damage here. The HG blew before it progressed to piston melt down.

Could have been a tune that was on the edge to begin with and simply one cylinder was over the edge on hot days or less than perfect gas. Could also be something like a clogged injector causing a lean cylinder. I know people think misfires are relatively uneventful but honestly, I've seen more people blow motors by trying to power through a misfire then by clear signs of detonation.

 

I've looked at these pictures several times trying to decide if detonation or not. If not then something tiny stayed in the cylinder for a long time. That seems unlikely.

 

I know I was getting knock really bad on 93 with very low timing. Switched to E85 to tune it after getting frustrated and later realized it was a big mistake. Knock went away but I guess the problem still existed.

My last E85 tune I was maxing out fuel pump, getting a bad misfire, and ended up blowing my freeze plug when logging to confirm I was out of fuel pump. I made a big mistake not trying to address the problem causing the knock on 93 and switching to E85.

Now I'm just trying to figure out if this problem looks serious enough to require me to pull the block to inspect things further and possibly rebuild?

 

I'll get a picture of the piston out of our racecar. It has a combination of det erosion and foreign object dings. There is a distinct difference. Det erosion is just a pit because the aluminum is literally falling off of the piston, it also typically happes more towards the outside edges of the crown. Foreign object dings look like craters, where you they have a raised ring around the outside of the pit..